The EMD DD35A, also known as the EMD DDA35, was a

diesel-electric locomotive A diesel locomotive is a type of railway locomotive in which the prime mover (locomotive), prime mover is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conv ...

of D-D

wheel arrangement In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and c ...

built by

General Motors The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...

Electro-Motive Division Progress Rail Locomotives, doing business as Electro-Motive Diesel (EMD), is an American manufacturer of diesel-electric locomotives, locomotive products and diesel engines for the rail industry. The company is owned by Caterpillar through its sub ...

exclusively for the

Union Pacific Railroad The Union Pacific Railroad , legally Union Pacific Railroad Company and often called simply Union Pacific, is a freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Paci ...

. They were a cab-equipped variant of the previous, cabless booster (

B unit B, or b, is the second letter of the Latin-script alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is '' bee'' (pronounced ), plural ''bees''. It re ...

)

EMD DD35 The EMD DD35 was a diesel-electric locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division for the Union Pacific Railroad and Southern Pacific Railroad. History In the early 1960s, Union Pacific started asking for ...

(sometimes erroneously called the 'DD35B'). Fifteen DD35A locomotives were built between May and July 1965; they were assigned road numbers 70 through 84. This request also led to the introduction of the

ALCO Century 855 The ALCO Century 855 was a model of diesel-electric locomotive built in 1964 by the American Locomotive Company for the Union Pacific Railroad. The locomotive was notable for being ALCO's most powerful diesel-electric locomotive and, at the ti ...

and

GE U50 The GE U50 was an eight-axle, diesel-electric locomotive built by GE Rail. They were twin-engined locomotives, combining two diesel engines. Configuration The U50 rode on four two-axle trucks, grouped in pairs linked by span bolsters, giving ...

. A further development of the 8 axle, twin-engined locomotive produced the final, best known type, the

DDA40X The EMD DDA40X is a 6,600 hp (4,943 kW) D-D locomotive, built by EMD from 1969 to 1971 exclusively for the Union Pacific Railroad. It is the most powerful diesel-electric locomotive model ever built on a single frame, having two 16- ...

"Centennial".

History

Like its cabless predecessor, the DD35A was essentially two

EMD GP35 The EMD GP35 is a 4-axle diesel-electric locomotive built by General Motors Electro-Motive Division between July 1963 and December 1965 and by General Motors Diesel between May 1964 and January 1966. 1251 examples were built for American railroa ...

locomotives on a common frame, riding on a pair of 4-

axle An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...

Flexicoil Flexicoil suspension is a type of secondary suspension for railway vehicles, typically having steel coil springs between the bogie trucks and chassis/frame of a passenger coach, goods freight wagon, or locomotive. Suspension systems using ste ...

trucks A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...

. The cab of a GP35 was fitted to the front end, requiring a longer frame than the DD35; the fuel tank beneath was lengthened, and the center pass-through walkway was offset a little to the rear because of the single cab. Another difference was that the DD35A was fitted with the new flared radiator section EMD was testing on its

EMD 645 The EMD 645 is a family of diesel engines that was designed and manufactured by the Electro-Motive Division of General Motors. While the 645 series was intended primarily for locomotive, marine and stationary engine use, one 16-cylinder versio ...

-engined demonstrators (the prototype

SD40 SD40 may refer to: * Canon PowerShot SD40, a digital camera * EMD SD40, a diesel-electric locomotive * South Dakota Highway 40 * SD-40 alcohol, ethanol denatured by adding denatonium benzoate Denatonium, usually available as denatonium benzoate (u ...

demonstrators). The DD35s were initially quite unreliable; some of this was blamed on sand from the internal sandboxes getting in electrical gear, so new sandboxes were fitted on the walkways in 1969. The DD35s were among the last EMD road units to be built with DC generators and old-fashioned switchgear, which were more maintenance intensive than the later AC/DC equipment. Once teething troubles had been overcome, the DD35s were reasonably successful, but they were less flexible than smaller units and thus with the economic downturn of the early 1980s they were withdrawn from service. They spent their final months of service operating around

Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the Capital (political), capital and List of cities and towns in Utah, most populous city of Utah, United States. It is the county seat, seat of Salt Lake County, Utah, Sal ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

before their retirement by 1981. No examples of the DD35 type were preserved.

Original buyers

References

* * * {{EMD SDs Diesel-electric locomotives of the United States DD35A Union Pacific Railroad locomotives D-D locomotives Railway locomotives introduced in 1965 Scrapped locomotives Freight locomotives Standard gauge locomotives of the United States

History

Original buyers

See also

References